A conventional solid-state imaging device includes a plurality of photodiodes formed on a semiconductor substrate in a grid shape, a plurality of color filter layers on each of these photodiodes and a plurality of microlenses formed on these color filter layers. The photodiode, the color filter layer and the microlense form pixel.
Each color filter layer formed for each pixel is, for example, any of a red color filter layer that allows light of a red wavelength to pass, a green color filter layer that allows light of a green wavelength to pass, and a blue color filter layer that allows light of a blue wavelength to pass. These color filter layers of three colors are formed in such a way that surfaces thereof are in one plane. The color filter layers of three colors are arranged in a Bayer array on the semiconductor substrate.
The color filter layer of each color has a different refractive index of light. However, each microlens is formed to have the same height on the color filter layer of each color whose surface is formed to be in one plane. Therefore, the focal position of light condensed to photodiodes after passing through each microlens and each color filter layer is different for each transmitted wavelength of the each color filter layer. As a result, sensitivity of light is different from pixel to pixel.
To adjust sensitivity of each pixel, the height of the microlens may be adjusted for each pixel. However, when a plurality of microlenses of mutually different heights is formed, it is necessary to repeat the manufacturing process of microlens two or more times. That is, first a plurality of microlenses of the uniform height is formed and then, predetermined microlenses are covered with a microlens material. Accordingly, only the predetermined microlenses become higher than other microlenses.
In contrast to the manufacturing method for microlenses described above, when a plurality of microlenses of the uniform height is formed, all microlenses can be manufactured in one process. Therefore, when a solid-state imaging device having a plurality of microlenses with mutually different heights is manufactured, there is a problem of an increased number of manufacturing processes compared with a case when a solid-state imaging device having a plurality of microlenses with a uniform height is manufactured.